There are a number of systems in the game that are underutilized or have many missed opportunities for improving or deepening the game.

• The patent system is very shallow. While it is nice having upgrades to yourself, it would be better if you could profit from them. Instead of just being an acquisition system that eventually runs out of steam and gets sold, why not add options to contract out services? Further depth would also be good. The point is that it should remain relevant throughout the game, instead of petering out once all the techs are taken, and could even have exclusive techs too (this or that).
  
  • Did you miss getting teleportation? Well, for a portion of the proceeds, we are willing to supply you with teleportation services for a certain period of time.
  • Need money? I'd be happy to buy that patent off of you.
  • Multiple levels of unlocking would also be good, ie better carbon scrubbing, silicon scrubbing (mars atmosphere is gull of sand), Stairway farming (makes your farms doubledeckers), etc.
• The colony is just sort of there. More dynamism in both construction and interaction with the players would make it more interesting. How about contracting to players for construction? How about offering players monopoly contracts on resources in exchange for discounts? Bidding and auctions for colony contracts in resource commitments, not just random items for money? Propaganda and advertising wars for colony business? Bribing politicians and admins?
• The offworld market is just somewhat "there". Why are these prices the way they are? Can we manipulate it?
• More interesting things out of the optimization center, instead of just flat percentage increases, possibly different depending on what techs you have from the patent lab?
• The whole shipping system is very bland. You just have these ships and can mess with them a little with a couple black market bits, but mostly it's non-interactive.
• More environmental effects. Earthquakes that expose new resources or destroy old deposits. Radiations storms that create famines. Biological plagues that contaminate water. unique isotopes and alotropes that make certain spaces special. There would obviously need to be some adjustments for this (forcing players to keep a claim on a now worthless non-functional mine spot without any way to adapt wouldn't work).
• More ways to deal with debt and manipulate yours and the opponent's stock prices. There should be ways to drive down the price of a target, or drive up the price of yours. Also ways to buy back your stock that has been bought out, which would allow some recovery.